Do the settings (0-7) on the adjustable slicing disc correspond to the thickness in mm?

No, the slicing result greatly depends on the softness of the ingredients you are slicing. The result is also influenced by the pressing force, i.e. the force you use to push the ingredients down the feeding tube. To find the setting that gives the desired thickness, simply try and slice the ingredient at a particular setting and readjust the slicing disc if you are not satisfied.